According to mobile wireless communication, a channel state of a radio link between each base station and each wireless terminal changes according to a time, and differently changes when a frequency is different. Hence, it is necessary to estimate channel states of downlink from each base station to each wireless terminal and uplink from each wireless terminal to each base station.
When each base station and each wireless terminal communicate by way of time-division multiplex, equivalence between uplink and downlink provides equivalent channel states of channels used for uplink and downlink.
[Patent Literature 1] Japanese Laid-open Patent Publication No. 2011-166570.
However, when a channel state is estimated based on an uplink sounding reference signal transmitted by each wireless terminal, a frequency band occupied by the uplink sounding reference signal does not necessarily match an uplink frequency band. In other words, a domain in which resource blocks at both ends of a system bandwidth in which a physical uplink control channel (PUCCH) is arranged are arranged cannot be covered by the uplink sounding reference signal in some cases.